A foreign tourist has been sexually assaulted on board a public transport van in Rio de Janeiro.

The tourist and her male companion were held against their will and beaten during a six-hour ordeal that began shortly after midnight on Saturday in the Copacabana beach neighbourhood, Brazilian police said.

Two men aged 20 and 22 have been arrested and a third is being sought in connection with the incident. The two arrested men were named by police as Jonathan Froudakis de Souza and Wallace Aparecido Silva.

Police said the suspects forced other passengers to get out of the van and sexually assaulted the female tourist inside the vehicle, one of a fleet of vans that serve bus routes and seat about a dozen people.

The tourists were driven to the poor suburban neighbourhood of São Gonçalo during the assault, where the two suspects were apprehended.

Froudakis de Souza (left), 20, and Wallace Aparecido Silva, 22, have been arrested in connection with the sexual assault of a tourist. Photograph: AFP/Getty Images

The incident raises new questions about security in Rio, which has cracked down on drug violence in preparation for hosting next year's World Cup and the 2016 Olympic Games. The city will also be playing host to World Youth Day, a Roman Catholic pilgrimage expected to draw two million people in late July.

The victims' nationalities have not been released, but local media have said the woman is American. Reports said the two had been studying Portuguese in Rio for about a month and that both left the country following the incident.

The statement said one of the victims' mobile phones was found in the suspects' possession. The suspects had also used a debit card belonging to one of the victims at two petrol stations, police said.

The Globo television network broadcast CCTV images of two men filling up the white van and showed police images of a metal bar the suspects are thought to have used to beat and intimidate the victims.

Police said a Brazilian woman had come forward to say she was also assaulted by the two suspects on 23 March.

In an interview with Globo television, commanding officer Alexandre Braga, who heads the Rio police unit specialising in crimes against tourists, said the suspects had gone on a sex crime spree.

"The characteristics of both crimes, both the Brazilian case and the one with the foreigners, lead us to believe that they wanted to have a 'party of evil', in quotes," Braga said. "The principal motive appears to have been the satisfaction of their lust." He added that the robbery and other crimes appeared to have been secondary.

The attack also drew comparisons with the fatal December beating and gang rape of a young woman on a bus in New Delhi, India. Six men beat a 23-year-old university student and her male friend after they boarded a private bus, sparking a wave of protests across India demanding stronger protection for women.

In Brazil, more than 5,300 cases of sexual assault were reported between January and June 2012, according to the country's health ministry.